Devices, System, and Methods using Transflective Mirrors with Rolling Shutter Sensors

ABSTRACT

A system and methods for implementing a transflective mirror as a rolling shutter sensor. The method includes. The method includes a controller setting a current state of an obfuscator to a transmissive state at a first point in time, the first point in time being a time when all pixels of an imaging sensor are in an active state. An imaging sensor then obtains an image of an object in a field of view of the imaging sensor. The image is obtained at a time when the obfuscator is in the transmissive state. The controller then sets the current state of the obfuscator to an obfuscative state at a point in time before a single pixel of the plurality of pixels is switched to an inactive state, wherein the active state of a pixel is a state in which a pixel is an active optical detector, and the inactive state is a state in which a pixel is not an active optical detector.

BACKGROUND

Typical barcode readers, such as handheld barcode readers, point of salescanners, and direct part marking scanners, require high quality,low-blur images to decode barcodes found in the images. Therefore,barcode scanners are motion sensitive which may be problematic due tothe nature of many applications of scanning barcodes. For example, aperson using a handheld scanner may move while the scanner obtains animage, or a person may quickly move an item across a scanners field ofview, both of which may cause a blurry, low-quality image. Additionally,it is desirable for the imaging sensor of a barcode reader to be exposedto a target image for just enough time to capture the image. Longerexposure times may cause blurring of the image, or expose the imagingsensor to more background noise, targeting radiation, or other noisesources preventing the barcode reader from decoding a barcode.

A shutter may be implemented to control the exposure time of an imagingsensor for a barcode reader. Rolling shutter sensors are imaging sensorsthat capture an image on adjacent rows of sensor pixels over differentperiods of time. Typically, a mechanical shutter is opened and closed,or rotated in the case of a rotary disc shutter, to expose the adjacentsets of pixels at different times. Rolling shutters are not typicallyimplemented in barcode readers due to the size and mechanicalrequirements of a rolling shutter sensor. As previously mentioned,rolling shutter sensors typically employ a mechanical shutter whichcannot open and close/rotate at the required frame rate for efficientimage capture and decoding as performed by a barcode reader.Additionally, mechanical shutters are bulky and require motors ormechanical actuators which would increase the weight, size, and pointsof possible failure of a barcode reader. Further, a rotational shuttercauses complications when trying to change exposure time and frame rate.As such, it could be beneficial for a barcode reader to implement arolling shutter sensor to improve image quality and resolution, whilenot having to simultaneously sacrifice performance, size, decodingefficacy or speed, and robustness, with respect to exposure times andframe rates, of the barcode imaging system.

SUMMARY

In an embodiment, the present invention is a method of capturing animage with an optical assembly for an optical imaging shutter system.The method comprises setting, by a controller, a current state of anobfuscator to a transmissive state at a first point in time, the firstpoint in time being a time when all pixels of an imaging sensor are inan active state, obtaining, by an imaging sensor having the plurality ofpixels, an image of an object in a field of view of the imaging sensor,the image obtained at a time when the obfuscator is in the transmissivestate, and setting, by the controller, the current state of theobfuscator to an obfuscative state at a point in time before a singlepixel of the plurality of pixels is switched to an inactive state,wherein the active state is a state in which a pixel is an activeoptical detector, and the inactive state is a state in which a pixel isnot an active optical detector.

In a variation of the current embodiment, the transmissive statecomprises a state wherein the obfuscator transmits more than 50% ofradiation incident on the obfuscator along an optical axis, and whereinthe obfuscative state is a state wherein the obfuscator obfuscates morethan 50% of radiation incident on the obfuscator along the optical axis.

In another variation of the current embodiment, the transition of theobfuscator from the obfuscative state to the transmissive states occursfaster than a temporal image blur threshold, wherein the temporal imageblur threshold is a time duration limit at which a transition of theobfuscator slower than the temporal image blur threshold results in animage that contains too much blur to decode.

In another embodiment, the present invention is an optical imagingshutter system comprising an obfuscator disposed along an optical axisconfigured to receive radiation from an object of interest with theobfuscator having (i) a first state wherein the obfuscator obfuscates amajority of radiation propagating along the optical axis, and (ii) asecond state wherein the obfuscator transmits a majority of radiationpropagating along the optical axis. A controller is communicativelycoupled to the obfuscator and configured to control a current state ofthe obfuscator, and an imaging sensor is disposed along the optical axisconfigured to receive an image of the object and to generate anelectrical signal indicative of the received image, the imaging sensorhaving a plurality of pixels with each pixel of the plurality of pixelshaving an (i) active state wherein the pixel is active as an opticalsensor for an active duration of the pixel, and (ii) an inactive statewherein the pixel is not active as an optical sensor for an inactiveduration of the pixel. A processor is in communication withcomputer-readable media storing machine readable instructions that, whenexecuted, cause the optical assembly to set, by the controller, thecurrent state of the obfuscator to the first state at a point in timewhen all pixels of the plurality of pixels are in an active state,obtain, by the imaging sensor, an image of the object during an imagecapture duration wherein all of the pixels of the plurality of pixelsare in the active state, and set, by the controller, the current stateof the obfuscator to the second state at a point in time before a singlepixel of the plurality of pixels is in an inactive state.

In yet another embodiment, the present invention is an optical assemblyfor an optical imaging shutter system. The optical assembly comprises anobfuscator disposed along an optical axis configured to receiveradiation from an object of interest with the obfuscator having (i) afirst state wherein the obfuscator obfuscates a majority of radiationpropagating along the optical axis, and (ii) a second state wherein theobfuscator transmits a majority of radiation propagating along theoptical axis, and an imaging sensor disposed along the optical axisconfigured to receive an image of the object and to generate anelectrical signal indicative of the received image, the imaging sensorhaving a plurality of pixels with each pixel of the plurality of pixelshaving an (i) active state wherein the pixel is active as an opticalsensor for an active duration of the pixel, and (ii) an inactive statewherein the pixel is not active as an optical sensor for an inactiveduration of the pixel.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying figures, where like reference numerals refer toidentical or functionally similar elements throughout the separateviews, together with the detailed description below, are incorporated inand form part of the specification, and serve to further illustrateembodiments of concepts that include the claimed invention, and explainvarious principles and advantages of those embodiments.

FIG. 1 illustrates an example barcode reader that uses an obfuscativeelement to operate as a rolling shutter sensor barcode reader forimaging an object of interest.

FIG. 2A illustrates an example of a pixel array of an imaging sensorhaving a plurality of pixel columns and pixel rows.

FIG. 2B illustrates a plot of pixel operation over time for a typicallyrolling shutter sensor.

FIG. 3 illustrates a block connection diagram of system including animaging reader as the barcode reader of FIG. 1 .

FIG. 4 is a flow diagram of a method for performing imaging of an objectof interest using a rolling shutter sensor barcode.

Skilled artisans will appreciate that elements in the figures areillustrated for simplicity and clarity and have not necessarily beendrawn to scale. For example, the dimensions of some of the elements inthe figures may be exaggerated relative to other elements to help toimprove understanding of embodiments of the present invention.

The apparatus and method components have been represented whereappropriate by conventional symbols in the drawings, showing only thosespecific details that are pertinent to understanding the embodiments ofthe present invention so as not to obscure the disclosure with detailsthat will be readily apparent to those of ordinary skill in the arthaving the benefit of the description herein.

DETAILED DESCRIPTION

Rolling shutter sensors are lost cost, high resolution imaging sensors.However, rolling shutter sensors are typical not viable for use inbarcode reader systems due to mechanical shutter speeds, motors, bulkycomponents, and the fact that they are very motion sensitive. Mechanicalshutters are slow compared to optical barcode decoding systemrequirements and are therefore not viable for use with barcode systems.The disclosed system and method enable the use of a rolling shuttersensor in a barcode imaging system by using a fast transitioningobfuscative optical element as a shutter.

Referring to FIG. 1 , an example barcode reader 100 is shown that usesan obfuscative element 103 to operate as a rolling shutter sensorbarcode reader for imaging an object of interest 102. The obfuscativeelement 103 is disposed inside of a housing 105 along an optical path Aof field of view 120 of an imaging sensor 125. A controller 107 controlsa state of the obfuscative element between an obfuscative state and atransmissive state. The obfuscative state is an optical state in whichthe obfuscative element obfuscates or obscures a majority of radiationfrom the imaging sensor 125, and the transmissive state is a an opticalstate wherein the obfuscator transmits a majority of radiation to theimaging sensor 125. The imaging sensor 125 is mounted on an imagingcircuit board which may provide power to the imaging sensor 125, controlof operation of the sensor 125, on/off board communications of data toand from the imaging sensor 125, among other operations and purposes.The imaging sensor 125 may be a CMOS device, or other imaging sensorcapable of functionality as a rolling shutter sensor. The imaging sensor125 may have a fixed exposure time, or the exposure time and rollingshutter functionality may be tuned to change the exposure time based onan object of interest, a distance of the object of interest, anillumination of the object of interest, etc.

A lens 108 is disposed along the optical path A to focus images receivedby the barcode reader 100 onto an imaging plane at the imaging sensor125. A window 110 is disposed along the optical axis A to provide atransmissive surface for optical radiation to pass along the opticalaxis into the housing 105. The window 110 acts as an aperture and may beuseful for preventing stray light and optical noise from entering thehousing 105. Further, the window may be a material or have coatings toperform as a filter to reduce noise or to select wavelengths of lightfor imaging at the imaging sensor 125. Each of the window 110, lens 108,and obfuscative element 103 are disposed to image the object of interest102 onto the imaging sensor 125.

While not illustrated, a person of ordinary skill in the art wouldrecognize that additional or fewer optical elements may be implementedalong the optical axis for imaging of the object of interest. Forexample, one or more additional lenses, wavelength filters, spatialfilters, polarizers, beam splitters, mirrors, waveplates, apertures, orother optical elements may be employed for imaging of the object ofinterest 102. In a configuration the object of interest 102 includes oneor more indicia indicative of information about the object of interest,the indicia being one or more of a 1D or 2D barcode, QR code, dynamic QRcode, UPC code, serial number, alphanumeric, a graphic, or anotherindicia.

The obfuscative element 103 may be a transflective mirror, such as thee-TransFlector™ from Kent Optronics, positioned within the housing 105along the optical path A. As a transflective mirror, the obfuscativeelement 103 can be switched between a transmissive state, in which amajority of light is allowed to pass through the transflective mirror,and a reflective state, in which a majority of light is reflected off ofthe transflective mirror. For example, the obfuscative element 103 mayswitch states in response to an electrical control signal received fromthe controller 107. With the transflective mirror in the reflectivestate, the transflective mirror reflects at least a first portion ofradiation in the field-of-view 120 of the imaging sensor 125. In thetransmissive state, the transflective mirror allows for opticalradiation within the field-of-view 120 to pass through the transflectivemirror 155 along the optical path A to the imaging sensor 125.Optionally, the transflective mirror could also be switched to apartially reflective state, in which the transflective mirror would bothreflect a portion of light, and transmit a portion of light. Such anexample may be useful in a system that images the object of interest 102while targeting radiation is provided to the barcode or object ofinterest. For example, the barcode reader 100 may further include atarget radiation source 113 that provides radiation to the object ofinterest 102 for a user of the barcode reader to reference whenpositioning the object of interest for scanning, or when position thebarcode reader 100 in the case of a handheld barcode reader. While notillustrated, the barcode reader 100 may further include an illuminationsource configured to provide illumination to a target or the object ofinterest 102 for imaging of the object of interest 102.

While described above as a transflective device, the obfuscative element103 does not need to reflect optical radiation. In the obfuscativestate, the obfuscative element 103 may absorb the radiation, orotherwise obscure the optical radiation to prevent the radiation fromreaching the imaging sensor 125, while the obfuscative element 103passes radiation to the imaging sensor 125 when in the transmissivestate. In configurations, the obfuscative element 103 may include one ormore of a transflective mirror, a different transflective element, anelectrochromic device, a polymer-dispersed liquid crystal film, oranother electrically controllable shutter element capable oftransitioning between states at a time scale operational for a barcodereader 100.

FIG. 2A is an example of a pixel array 200 of (or a portion thereof) animaging sensor. The pixel array 200 may be operated as a rolling shuttersensor as the imaging the sensor 125 of FIG. 1 . The pixel array 200 hasa plurality of columns of pixels C₁ through C₈, and a plurality of rowsof pixels R₁ through R₈ with each pixel 202 belong to one column and onerow. FIG. 2B is a plot of pixel operation over time for a typicallyrolling shutter sensor. Operation of the barcode reader 100 and imagingsensor 125 of FIG. 1 will be described with simultaneous reference toFIGS. 1, 2A, and 2B as a rolling shutter sensor.

Each pixel 202 of the pixel array 200 may be activated and deactivatedindependently or in groups by the circuit board 127, or by anothercontroller. When activated, a pixel is “on” and is actively detectinglight or optical radiation for capturing an image. When deactivated, apixel is “off” and is not optically active for imaging. As illustratedin FIG. 2B, each pixel has various states during operation. A pixel isfirst reset to clear any residual charge from the pixel or to reset amemory of the pixel. The pixel is then activated to detect opticalradiation and the pixel generates an electrical signal indicative of thedetected radiation and integrates the electrical signal. The integratedsignal is then stored in a memory, and eventually the integrated signalis read out from the memory for image stitching, and processing togenerate an image and to identify indicia indicative of the object ofinterest 102. Each of the steps of resetting the pixel, detectingradiation and integrating the electrical signal, storing the integratedsignal in memory, and reading out of the signal takes an amount of timethat is dependent on the optical and electrical components of the pixel.

Initially, all of the pixels are in a deactivated state before a timet_(i), and the obfuscative element 103 is initially in the obfuscativestate. A controller of the circuit board 127 may then reset the firstcolumn of pixels C₁, and at a time t_(i1) the first column of pixels C₁then detects optical radiation, generates an electrical signalindicative of the detected radiation, and begins integrating theelectrical signal. At a time subsequent to t_(i1), the controller of thecircuit board 127 resets the second column of pixels C₂, and at a timet_(i2) the second column of pixels C₂ begins detecting opticalradiation, generating an electrical signal indicative of the radiation,and begins integrating the electrical signal. Subsequent columns ofpixels C₃-C₈ are each independently reset, and activated at respectivetimes t_(i3) to t_(i8), to detect radiation, generate electricalsignals, and integrate according to the predescribed pattern.

At the time t_(i8) all eight of the pixel columns C₁-C₈ are activatedand each pixel is on. Therefore, at the time t_(i8) the controller 107changes the state of the obfuscative element 103 from the obfuscativestate to the transmissive state. The obfuscative element 103 thentransmits optical radiation from the object of interest 102 to theimaging sensor 125. Each of the pixels of the pixel array 200 thendetect and generate and integrate electrical signals indicative of thedetected radiation. The circuit board 127 (or a controller thereon) thendeactivates the first column of pixels C₁ at a time t_(f1). Thecontroller 107 changes the state of the obfuscative element 103 from thetransmissive state to the obfuscative state at the time t_(t2) at thesame time as the first column of pixels C₁ is deactivated. In thecurrent example, the duration of the transmissive state of theobfuscative element 103 (i.e., the duration t₂-t₁) is the same amount oftime as the duration in which all of the pixels 202 of the pixel array200 are active (i.e., the duration t_(i8)-t_(f1)). Therefore, the pixels202 only absorb light while all pixels are active which reduces theexposure time of the imaging sensor 125. Typically, in a rolling shuttersensor, each row or column of pixels is exposed to radiation from anobject at slightly different times creating greater blur than thedisclosed system and method. Using the obfuscative element 103 to ensurethat all of the pixels 202 are exposed to the radiation from the objectof interest 102 reduces blur of an image of the object of interest 102,and increases the efficiency of decoding of indicia by the barcode read100.

In configurations, the controller 107 may change the state of theobfuscative element 103 to the transmissive state at a time before allof the columns of pixels are active (i.e., a time before the timet_(i8)). For example, the target radiation source 113 may provide targetradiation in the form of a crosshair or a box to indicate the field ofview 120 to a user of the barcode reader 100. The targeting radiationmay reflect off of the object of interest 102, or any surfaces such asan aperture window, optics, or another surface and the reflected targetradiation may be reflected toward the imaging sensor 125. To prevent thetargeting radiation from being captured in an image obtained by theimaging sensor 125, the target radiation source 113 may selectivelyprovide target radiation during times when the obfuscative element 103is in the obfuscative state, and not provide target radiation when theobfuscative element is in the transmissive state. It may be desirable todetect a portion of the target radiation in an image of the object ofinterest to further assist with image processing and decoding of indiciain the image. As such, the controller 107 may change the state of theobfuscative element 103 to the transmissive state at a time before thetime t_(i8) that the final column of pixels C₈ is active. Alternatively,the target radiation source 113 may provide target radiation for aperiod of time after the controller 107 changes the state of theobfuscative element 103 to the transmissive state at time t₁. Asdescribed further herein, the controller 107 may change the state of theobfuscator 103 to the obfuscative state before any pixels or columns ofpixels are deactivated. In other examples, the controller 107 may changethe state of the obfuscator 103 to the obfuscative state after one ormore of the pixels, or one or more columns of pixels, have beendeactivated depending on the time it takes for the obfuscator totransition from the transparent to the obfuscative state. Changing theobfuscator to the obfuscative state after one or more pixels aredeactivated may allow a maximum amount of light through to the imagingsensor 125 in order to maximize the light exposure of pixels andminimize any motion blur that would happen in other rolling shuttersensor technologies.

After the first column of pixels C₁ has integrated the electricalsignals of detected radiation, the controller 107 deactivates the firstcolumn of pixels at time t_(tf1) and the first column of pixels storesthe integrated signals in a memory. The circuit board 127 may thenretrieve signals indicative of the integrated signals from the memoryfor performing image processing and decoding of indicia of the object ofinterest 102. The circuit board may provide the retrieved signals toother processor and systems for performing image processing and decodingof the indicia of the object of interest 102. Each of the second througheighth columns of pixels C₂-C₈ then is deactivated at respective timest_(f2)-t_(f8). Further, each column of pixels C₂-C₈ stores correspondingintegrated signals in memory, and the memory may be readout by thecircuit board 127 or by another device. As illustrated in FIG. 2B, thedescribed system may allow for a reduced amount of memory required forstoring the integrated signals as integrated signals for each column maybe read out before a subsequent column's integrated signals are storedin the memory. Therefore, the described systems may provide a means fora more compact and less expensive implementation of a barcode reader.

FIG. 3 illustrates a block connection diagram of system 300 including animaging reader as the barcode reader 100. In FIG. 3 the barcode reader100 may have one or more processors and one or more memories storingcomputer executable instructions to perform operations associated withthe systems and methods as described herein. The barcode reader 100includes a network input/output (I/O) interface for connecting thereader to a server 112, an inventory management system (not shown), andother imaging readers. These devices may be connected via any suitablecommunication means, including wired and/or wireless connectivitycomponents that implement one or more communication protocol standardslike, for example, TCP/IP, WiFi (802.11b), Bluetooth, Ethernet, or anyother suitable communication protocols or standards. The barcode reader106 further includes a display for providing information such as visualindicators, instructions, data, and images to a user.

In some embodiments, the server 112 (and/or other connected devices) maybe located in a scanning station or point of sales system that includesthe barcode reader 100. In other embodiments, the server 112 (and/orother connected devices) may be located at a remote location, such as ona cloud-platform or other remote location. In still other embodiments,server 112 (and/or other connected devices) may be formed of acombination of local and cloud-based computers.

The server 112 is configured to execute computer instructions to performoperations associated with the systems and methods as described herein.The server 112 may implement enterprise service software that mayinclude, for example, RESTful (representational state transfer) APIservices, message queuing service, and event services that may beprovided by various platforms or specifications, such as the J2EEspecification implemented by any one of the Oracle WebLogic Serverplatform, the JBoss platform, or the IBM WebSphere platform, etc. Othertechnologies or platforms, such as Ruby on Rails, Microsoft .NET, orsimilar may also be used.

In the illustrated example, the barcode reader 100 includes a lightsource 302, which may be a visible light source (e.g., a LED emitting at640 nm) or an infrared light source (e.g., emitting at or about 700 nm,850 nm, or 940 nm, for example), capable of generating an illuminationbeam that illuminates the field of view 120 for imaging over an entireworking distance of that field of view 120. That is, the light source302 is configured to illuminate over at least the entire field of view120. The illumination intensity of the light source 302 and thesensitivity of an imaging reader can determine the further and closestdistances (defining the distance of the working range, also termed thescanning range) over which a good can be scanned, and a barcode on thegood can be decoded. The light source 302 is controlled by processor andmay be a continuous light source, an intermittent light source, or asignal-controlled light source, such as a light source trigged by anobject detection system coupled (or formed as part of though not shown)to the barcode reader 100. The light source may be an omnidirectionallight source.

The barcode reader 100 further includes an imaging arrangement 304having an imaging sensor 306 positioned to capture images of anilluminated target, such as the object of interest 102 or another objecthaving an indicia for decoding, within a working range of the field ofview 120. In some embodiments, the imaging sensor 306 is formed of oneor more CMOS imaging arrays. An obfuscator 310 is positioned between theimaging sensor 306 and a window 312 of the imaging reader 100. Acontroller 314 is coupled to the obfuscator 310 and controls theobfuscator 310 to control a state of the obfuscator. The state of theobfuscator 310 is an optical transmission state wherein the controller314 controls the obfuscator 310 to allow a portion of optical radiationto pass through the obfuscator. The controller may control theobfuscator 310 in a binary manner wherein the obfuscator has atransmissive state that transmits greater than 50% of radiation incidenton the obfuscator 310, and an obfuscative state that blocks or reflectsgreater than 50% of incident radiation on the obfuscator 310. Thecontroller 314 may control the obfuscator 310 to set a plurality ofstates having transmissions of 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%,90%, or approximately 100%±5%. Additionally, the controller 314 maycontrol the obfuscator 310 to have a plurality of states with each statehaving a transmission percentage of less than 10%, less than 20%, lessthan 30%, less than 40%, less than 50%, less than 60%, less than 70%,less than 80%, less than 90%, less than 100%, greater than 10%, greaterthan 20%, greater than 30%, greater than 40%, greater than 50%, greaterthan 60%, greater than 70%, or greater than 80%, greater than 90%. Thecontroller 314 may control the obfuscator to have an obfuscative statethat has a transmission percentage of less than 10%, less than 20%, lessthan 30%, less than 40%, less than 50%, less than 60%, less than 70%,less than 80%, less than 90%, or less than 100%.

In the illustrated example, the controller 314 is in directcommunication with the obfuscator 310. In embodiments, the controller314 may be in direct or indirect communication (i.e., through a network,through intermediate system components, through amplifiers, etc.) withthe obfuscator 310. The controller 314 may include one or more voltagesources, amplifiers, current sources, or another source of electricity,electric field, or magnetic field to control the transmission of theobfuscator 310. In embodiments, the controller is configured to accessone or more obfuscator state parameters (e.g., optical state transitionpercentages, optical state durations, etc.) stored in the barcode reader100, stored on the server 112, or stored on another medium.

The obfuscator 310 may include one or more of a transflector,electrochromic device, polymer-dispersed liquid crystal film, or anotheroptical device with an electrically tunable transmission. The obfuscatormay be any electrically switchable optical element that can transitionfrom a transparent, or near transparent state (e.g., more than 50%transmissive), to an opaque or near opaque state (e.g., less than 50%transmissive). The optical transmission of the obfuscator 310 may becontrollable by a voltage, current, electric potential, electric field,or magnetic field among other potential electrical control signals.

In embodiments, the imaging sensor 306 may be a charge coupled device, arolling shutter sensor, or another solid-state imaging device. Theimaging sensor 306 may be a one megapixel sensor with pixels ofapproximately three microns in size. In embodiments, the imaging sensor306 includes a sensor having an active area of 3 millimeters, 4.5millimeters, 5 millimeters, 6.8 millimeters, 7.13 millimeters, less than5 millimeters, less than 10 millimeters, or less than 50 millimeters.The imaging sensor 112 may have a total of about 1 megapixels, 2megapixels, 2.3 megapixels, 5 megapixels, 5.1 megapixels or more than 5megapixels. Further, the imaging sensor 112 may include sensors withpixels having dimensions of less than 10 microns, less than 5 microns,less than 3 microns, or less than 2 microns in size in at least onedimension of the pixel. In embodiments, the image sensor includes a lensassembly configured to capture images with a modulation transferfunction of 40% at 160 line pairs per millimeter. The imaging sensor 306may include a rolling shutter sensor as described in reference to FIGS.2A and 2B that includes a controller that controls the states of rows orcolumns of pixels of the imaging sensor 306. For example, the controller314 may be in communication with the imaging sensor 306 to controlpixels, rows of pixels, columns of pixels, or any plurality of pixels ofthe imagine sensor. The controller 314 may control pixels of the imagingsensor 306 to set pixels to an optically active state or an opticallyinactive state. The optically active state is considered an “on” statewherein the a pixel detectors radiation and generates an electric signalindicative of the detected, radiation, and the optically inactive stateis a state wherein a pixel does not generate an electric signalindicative of detected radiation.

In some exemplary embodiments, the barcode reader 106 is implemented ina handheld bar code scanner device. When the handheld scanner is placedwithin a stationary cradle thereby establishing an upright scanningposition, the handheld scanner may automatically sense that placementand enter the hands-free mode. In other exemplary embodiments, thebarcode reader 106 is implemented as a multi-plane scanner, such as abioptic scanner or a point of sale system.

FIG. 4 is a flow diagram of a method 400 for performing imaging of anobject of interest using a rolling shutter sensor barcode. The method400 may be performed by the barcode reader 100 illustrated in FIGS. 1and 3 using the obfuscative element 103 as a shutter. With simultaneousreference to FIGS. 1-4 , the method 400 includes the controller 314setting an initial state of the obfuscator 310 and pixels of the imagingsensor 306 at block 402. The controller sets the initial state of theobfuscator 310 to an obfuscative state that transmits less than 50% ofradiation incident on the obfuscator 310. The controller 314 sets thestate of the pixels of the imaging sensor 306 to an optically inactivestate. Therefore, radiation does not pass through the obfuscator 310,and the imaging sensor 306 does not detect any radiation or generateelectrical signals indicative of any detected radiation.

The controller 314 sets at least a portion of pixels of the imagingsensor 306 to an optically active state at block 404. The controller 314may set a column of pixels, a row of pixels, or any subset of pixels tothe optically active state. As described in reference to FIGS. 2A and2B, the controller may set adjacent columns, or rows, or pixels to theactive state sequentially over a period of time until all of the pixelsof the imaging sensor 306 are set to the optically active state.

The controller 314 then sets the state of the obfuscator 310 to thetransmissive state at block 406. The transmissive state may be a statein which the obfuscator transmits greater than 50% of radiation incidenton the obfuscator. The imaging sensor 306 then obtains an image of theobject of interest 102 at block 408. The image contains indiciaindicative of the object of interest for decoding of the indicia. Theimage sensor 306 then generates an electrical signal indicative of theobtained image and stores the signal in a memory or provides the signalto another system or network for processing and decoding of the indicia.

The controller 314 then sets the obfuscator 310 to the obfuscative stateat block 410. In the obfuscative state, the obfuscator blocks light fromreaching the imaging sensor and therefore active pixels of the imagingsensor receive little to no light. The duration of time that theobfuscator 310 is in the transmissive state determines the exposure timeof pixels of the imaging sensor 306. In configurations, the exposuretime of the imaging sensor may be fixed, or the controller 314 maychange the exposure time of the imaging sensor 306 based on anillumination intensity of the object of interest 102, a distance of theobject of interest, a specular reflectivity or diffuse reflectivity ofthe object of interest, or another optical parameter. In embodiments,the imaging sensor 310 may have a fixed exposure time and the controller314 may control the obfuscator states according to the fixed exposuretime of the imaging sensor 310. The controller 314 then sets at least aportion of the plurality of pixels of the imaging sensor 306 to theoptically inactive state at block 412. The controller 314 continues toset pixels to the inactive state until all of the pixels of the imagingsensor 306 are set to the inactive state. In one example, as describedin reference to FIGS. 2A and 2B, the controller 314 may sequentially setcolumns of pixels or rows of pixels to the inactive state until all ofthe pixels are set to the inactive state.

After a pixel, or column of pixels, has been deactivated, the pixel maysend data indicative of the detected radiation to another processor, amemory, or off board to another system for further storage orprocessing. Further, a processor or system may query each pixel orcolumn of pixels to obtain signal data indicative of detected radiation.After all of the pixels; or columns of pixels, have provided signal datato a processor, memory, or system for processing and generating an imageof the object of interest 102 the method 400 may return to block 404 andthe controller 314 may set a column of pixels, a row of pixels, or anysubset of pixels to the optically active state allowing for the imagingto repeat blocks 404 through 412 to obtain another image of an object ofinterest. The method 400 may be performed iteratively capturing aplurality of images of one or more objects of interest. The method 400may be terminated manually by a user of the barcode reader 100, orautomatically after one or more of a predetermined number of images havebeen obtained. Further, the barcode reader 100 may terminate the method400 based on analysis of an obtained image determined to have an imagequality value at or above an image quality value threshold.

In configurations, the transition of the obfuscator 310 from theobfuscative state to the transmissive state, or from the transmissivestate to the obfuscative state, occurs faster than an image blurthreshold. The image blur threshold is a duration of time limit at whicha slower obfuscator state transition results in a captured image that isunable to be decoded by the barcode reader 100. Obfuscator transitionsfaster than the image blur threshold result in captured images that areable to be decoded by the barcode reader 100. The time value of theimage blur threshold may be dependent on characteristics of the imagingsensor 306, for example an exposure time, temporal resolution, spatialresolution, number of pixels, size of pixels, type of sensor, etc.Further, the image blur threshold may depend on the static or dynamicnature of the object of interest 102 being scanned, for example thespeed at which an object of interest traverses the field of view 120, anillumination of the object of interest, a distance of the object ofinterest, etc.

The transition speed of the obfuscator 310 may be controllable toprovide different resultant obtained images. The controller 314 maycause the obfuscator 310 to begin transitioning from the obfuscativestate to the transmissive state before all the pixels are in the activestate, and further the controller 314 may transition the obfuscator 310back to the obfuscative state just after some of the pixels aredeactivated and signal data is being read out. Such an implementationwould maximize light exposure of the pixels, but could result in somemotion blur in an obtained image, although the motion blur would be lessthan with other rolling shutter systems.

The method 400 may further include the light source 302 providingillumination to the object of interest 102 in the field of view 120during periods of time when the obfuscator 310 is in the transmissivestate. This allows for illumination of the object of interest 102 insituations when ambient light is not bright enough to obtain a qualityimage of the object of interest 102 for decoding of indicia in theimage. Further, the light source 302 may turn off during periods of timewhen the obfuscator is in the obfuscative state. The method 400 may alsoinclude providing, by the target radiation source 303, target radiationto the object of interest at various times. For example, the targetradiation source 303 may provide target radiation to a region in thefield of view 120 only during periods of time when the obfuscator 310 isin the obfuscative state to prevent the image sensor 306 from imagingany of the target radiation. The target radiation source 303 may providetarget radiation during periods of time when the obfuscator 310 is inthe obfuscative state and the transmissive state so that an image of theobject of interest includes the target radiation for assisting in imageprocessing and decoding indicia in the obtained image.

In the foregoing specification, specific embodiments have beendescribed. However, one of ordinary skill in the art appreciates thatvarious modifications and changes can be made without departing from thescope of the invention as set forth in the claims below. Accordingly,the specification and figures are to be regarded in an illustrativerather than a restrictive sense, and all such modifications are intendedto be included within the scope of present teachings.

The benefits, advantages, solutions to problems, and any element(s) thatmay cause any benefit, advantage, or solution to occur or become morepronounced are not to be construed as a critical, required, or essentialfeatures or elements of any or all the claims. The invention is definedsolely by the appended claims including any amendments made during thependency of this application and all equivalents of those claims asissued.

Alternative implementations of the examples represented by the blockdiagram of the system 200 of FIG. 2 includes one or more additional oralternative elements, processes and/or devices. Additionally oralternatively, one or more of the example blocks of the diagram may becombined, divided, re-arranged or omitted. Components represented by theblocks of the diagram are implemented by hardware, software, firmware,and/or any combination of hardware, software and/or firmware. In someexamples, at least one of the components represented by the blocks isimplemented by a logic circuit. As used herein, the term “logic circuit”is expressly defined as a physical device including at least onehardware component configured (e.g., via operation in accordance with apredetermined configuration and/or via execution of storedmachine-readable instructions) to control one or more machines and/orperform operations of one or more machines. Examples of a logic circuitinclude one or more processors, one or more coprocessors, one or moremicroprocessors, one or more controllers, one or more digital signalprocessors (DSPs), one or more application specific integrated circuits(ASICs), one or more field programmable gate arrays (FPGAs), one or moremicrocontroller units (MCUs), one or more hardware accelerators, one ormore special-purpose computer chips, and one or more system-on-a-chip(SoC) devices. Some example logic circuits, such as ASICs or FPGAs, arespecifically configured hardware for performing operations (e.g., one ormore of the operations described herein and represented by theflowcharts of this disclosure, if such are present). Some example logiccircuits are hardware that executes machine-readable instructions toperform operations (e.g., one or more of the operations described hereinand represented by the flowcharts of this disclosure, if such arepresent). Some example logic circuits include a combination ofspecifically configured hardware and hardware that executesmachine-readable instructions. The above description refers to variousoperations described herein and flowcharts that may be appended heretoto illustrate the flow of those operations. Any such flowcharts arerepresentative of example methods disclosed herein. In some examples,the methods represented by the flowcharts implement the apparatusrepresented by the block diagrams. Alternative implementations ofexample methods disclosed herein may include additional or alternativeoperations. Further, operations of alternative implementations of themethods disclosed herein may combined, divided, re-arranged or omitted.In some examples, the operations described herein are implemented bymachine-readable instructions (e.g., software and/or firmware) stored ona medium (e.g., a tangible machine-readable medium) for execution by oneor more logic circuits (e.g., processor(s)). In some examples, theoperations described herein are implemented by one or moreconfigurations of one or more specifically designed logic circuits(e.g., ASIC(s)). In some examples the operations described herein areimplemented by a combination of specifically designed logic circuit(s)and machine-readable instructions stored on a medium (e.g., a tangiblemachine-readable medium) for execution by logic circuit(s).

As used herein, each of the terms “tangible machine-readable medium,”“non-transitory machine-readable medium” and “machine-readable storagedevice” is expressly defined as a storage medium (e.g., a platter of ahard disk drive, a digital versatile disc, a compact disc, flash memory,read-only memory, random-access memory, etc.) on which machine-readableinstructions (e.g., program code in the form of, for example, softwareand/or firmware) are stored for any suitable duration of time (e.g.,permanently, for an extended period of time (e.g., while a programassociated with the machine-readable instructions is executing), and/ora short period of time (e.g., while the machine-readable instructionsare cached and/or during a buffering process)). Further, as used herein,each of the terms “tangible machine-readable medium,” “non-transitorymachine-readable medium” and “machine-readable storage device” isexpressly defined to exclude propagating signals. That is, as used inany claim of this patent, none of the terms “tangible machine-readablemedium,” “non-transitory machine-readable medium,” and “machine-readablestorage device” can be read to be implemented by a propagating signal.

In the foregoing specification, specific embodiments have beendescribed. However, one of ordinary skill in the art appreciates thatvarious modifications and changes can be made without departing from thescope of the invention as set forth in the claims below. Accordingly,the specification and figures are to be regarded in an illustrativerather than a restrictive sense, and all such modifications are intendedto be included within the scope of present teachings. Additionally, thedescribed embodiments/examples/implementations should not be interpretedas mutually exclusive, and should instead be understood as potentiallycombinable if such combinations are permissive in any way. In otherwords, any feature disclosed in any of the aforementionedembodiments/examples/implementations may be included in any of the otheraforementioned embodiments/examples/implementations.

The benefits, advantages, solutions to problems, and any element(s) thatmay cause any benefit, advantage, or solution to occur or become morepronounced are not to be construed as a critical, required, or essentialfeatures or elements of any or all the claims. The claimed invention isdefined solely by the appended claims including any amendments madeduring the pendency of this application and all equivalents of thoseclaims as issued.

Moreover in this document, relational terms such as first and second,top and bottom, and the like may be used solely to distinguish oneentity or action from another entity or action without necessarilyrequiring or implying any actual such relationship or order between suchentities or actions. The terms “comprises,” “comprising,” “has”,“having,” “includes”, “including,” “contains”, “containing” or any othervariation thereof, are intended to cover a non-exclusive inclusion, suchthat a process, method, article, or apparatus that comprises, has,includes, contains a list of elements does not include only thoseelements but may include other elements not expressly listed or inherentto such process, method, article, or apparatus. An element proceeded by“comprises . . . a”, “has . . . a”, “includes . . . a”, “contains . . .a” does not, without more constraints, preclude the existence ofadditional identical elements in the process, method, article, orapparatus that comprises, has, includes, contains the element. The terms“a” and “an” are defined as one or more unless explicitly statedotherwise herein. The terms “substantially”, “essentially”,“approximately”, “about” or any other version thereof, are defined asbeing close to as understood by one of ordinary skill in the art, and inone non-limiting embodiment the term is defined to be within 10%, inanother embodiment within 5%, in another embodiment within 1% and inanother embodiment within 0.5%. The term “coupled” as used herein isdefined as connected, although not necessarily directly and notnecessarily mechanically. A device or structure that is “configured” ina certain way is configured in at least that way, but may also beconfigured in ways that are not listed.

The Abstract of the Disclosure is provided to allow the reader toquickly ascertain the nature of the technical disclosure. It issubmitted with the understanding that it will not be used to interpretor limit the scope or meaning of the claims. In addition, in theforegoing Detailed Description, it can be seen that various features aregrouped together in various embodiments for the purpose of streamliningthe disclosure. This method of disclosure is not to be interpreted asreflecting an intention that the claimed embodiments require morefeatures than are expressly recited in each claim. Rather, as thefollowing claims reflect, inventive subject matter may lie in less thanall features of a single disclosed embodiment. Thus, the followingclaims are hereby incorporated into the Detailed Description, with eachclaim standing on its own as a separately claimed subject matter.

1. A method of capturing an image with an optical assembly for anoptical imaging shutter system, the method comprising: setting, by acontroller, a current state of an obfuscator to a transmissive state ata first point in time, the first point in time being a time when allpixels of an imaging sensor are in an active state; obtaining, by animaging sensor having the plurality of pixels, an image of an object ina field of view of the imaging sensor, the image obtained at a time whenthe obfuscator is in the transmissive state; and setting, by thecontroller, the current state of the obfuscator to an obfuscative stateat a point in time before a single pixel of the plurality of pixels isswitched to an inactive state, wherein the active state is a state inwhich a pixel is an active optical detector, and the inactive state is astate in which a pixel is not an active optical detector.
 2. The methodof claim 1, wherein the obfuscator comprises a transflector.
 3. Themethod of claim 1, wherein the obfuscator comprises an electrochromicdevice.
 3. The method of claim 1, wherein the obfuscator comprises anpolymer-dispersed liquid crystal film.
 4. The method of claim 1, whereinthe imaging sensor comprises a rolling shutter sensor.
 5. The method ofclaim 1, wherein the transmissive state comprises a state wherein theobfuscator transmits more than 50% of radiation incident on theobfuscator along an optical axis, and wherein the obfuscative state is astate wherein the obfuscator obfuscates more than 50% of radiationincident on the obfuscator along the optical axis.
 6. The method ofclaim 1, further comprising, providing, by an illumination source,illumination to the object during a period of time when the obfuscatoris in the transmissive state.
 7. The method of claim 1, furthercomprising, providing, by a targeting source, target illumination in thefield of view of the imaging sensor during a period of time when theobfuscator is in the obfuscative state.
 8. The method of claim 1,wherein the imaging sensor has a fixed exposure time; and whereinsetting the current state of the obfuscator to the transmissive statecomprises setting the state of the obfuscator to the transmissive statefor a duration dependent upon the fixed exposure time of the imagingsensor.
 9. The method of claim 1, wherein the transition of theobfuscator from the obfuscative state to the transmissive states occursfaster than a temporal image blur threshold, wherein the temporal imageblur threshold is a time duration limit at which a transition of theobfuscator slower than the temporal image blur threshold results in animage that contains too much blur to decode.
 10. An optical imagingshutter system comprising: an obfuscator disposed along an optical axisconfigured to receive radiation from an object of interest, theobfuscator having (i) a first state wherein the obfuscator obfuscates amajority of radiation propagating along the optical axis, and (ii) asecond state wherein the obfuscator transmits a majority of radiationpropagating along the optical axis; a controller communicatively coupledto the obfuscator and configured to control a current state of theobfuscator; an imaging sensor disposed along the optical axis configuredto receive an image of the object and to generate an electrical signalindicative of the received image, the imaging sensor having a pluralityof pixels with each pixel of the plurality of pixels having an (i)active state wherein the pixel is active as an optical sensor for anactive duration of the pixel, and (ii) an inactive state wherein thepixel is not active as an optical sensor for an inactive duration of thepixel; a processor and computer-readable media storing machine readableinstructions that, when executed, cause the optical assembly to: set, bythe controller, the current state of the obfuscator to the second stateat a point in time when all pixels of the plurality of pixels are in anactive state; obtain, by the imaging sensor, an image of the objectduring an image capture duration wherein all of the pixels of theplurality of pixels are in the active state; and set, by the controller,the current state of the obfuscator to the first state at a point intime before a single pixel of the plurality of pixels is in an inactivestate.
 11. The system of claim 10, wherein the obfuscator comprises oneof a transflector, an electrochromic device, or a polymer-dispersedliquid crystal film.
 12. The system of claim 10, wherein the imagingsensor comprises a rolling shutter sensor.
 13. The system of claim 10,wherein the second state comprises a state wherein the obfuscatortransmits more than 50% of radiation incident on the obfuscator along anoptical axis, and wherein the first state is a state wherein theobfuscator obfuscates more than 50% of radiation incident on theobfuscator along the optical axis.
 14. The system of claim 10, furthercomprising, an illumination source that provides illumination to theobject during a period of time when the obfuscator is in the secondstate.
 15. The system of claim 10, further comprising, providing, by atargeting source, target illumination in the field of view of theimaging sensor during a period of time when the obfuscator is in thefirst state.
 16. The system of claim 10, wherein the imaging sensor hasa fixed exposure time; and wherein to set the current state of theobfuscator to the second state the computer-readable media cause theoptical assembly to set the state of the obfuscator to the second statefor a duration of time dependent upon the fixed exposure time of theimaging sensor.
 17. The system of claim 10, wherein a transition of theobfuscator from the first state to the second states occurs faster thana temporal image blur threshold, wherein the temporal image blurthreshold is a time duration limit at which a transition of theobfuscator slower than the temporal image blur threshold results in animage that contains too much blur to decode.
 18. An optical assembly foran optical imaging shutter system, the optical assembly comprising: anobfuscator disposed along an optical axis configured to receiveradiation from an object of interest, the obfuscator having (i) a firststate wherein the obfuscator obfuscates a majority of radiationpropagating along the optical axis, and (ii) a second state wherein theobfuscator transmits a majority of radiation propagating along theoptical axis; and an imaging sensor disposed along the optical axisconfigured to receive an image of the object and to generate anelectrical signal indicative of the received image, the imaging sensorhaving a plurality of pixels with each pixel of the plurality of pixelshaving an (i) active state wherein the pixel is active as an opticalsensor for an active duration of the pixel, and (ii) an inactive statewherein the pixel is not active as an optical sensor for an inactiveduration of the pixel.
 19. The optical assembly of claim 18, wherein theobfuscator comprises one of a transflector, an electrochromic device, ora polymer-dispersed liquid crystal film.
 20. The optical assembly ofclaim 18, wherein a transition of the obfuscator from the first state tothe second states occurs faster than a temporal image blur threshold,wherein the temporal image blur threshold is a time duration limit atwhich a transition of the obfuscator slower than the temporal image blurthreshold results in an image that contains too much blur to decode.